1. Field of Invention
The present invention relates generally to dehydration of food and more particularly to novel dehydrators and methods for home use in preserving food under close time, temperature and humidity restraints.
2. Prior Art
Prior art proposals for preservation of food through dehydration have included sun drying, kitchen oven drying and special equipment drying. Naturally, the time and temperature requirements will vary substantially depending upon the food being dehydrated and the type of equipment, if any, being used. Time and temperature data for a given food is normally determined empirically and there are a number of publications available indicating time and temperature conditions which produce the best results for a given meat, vegetable or fruit to be dehydrated. For example, see Mountain Valley Book of Home Food Dehydrating by Jay P. and Shirley S. Bills, 1973, which was printed by Keith W. Watkins, Logan, Utah. The end object in each case is to preserve food products in which so much of the product's natural moisture is removed that spoilage micro-organisms (yeasts, molds and bacteria), even though present in a living condition in the dehydrated product, are unable to grow or multiply.
Sun curing is as old as field cutting and drying of hay and has been applied to fruits, vegetables and meats for human consumption. The method, however, is the most unsatisfactory of those available since it demands a "rainless" season of bright sunshine and high temperature coincident with the period of time when the vegetable or fruit is at full maturity and not yet spoiled. If a succession of sunny days does not occur at the proper time, the fruits and vegetables will spoil.
Kitchen oven drying is also normally unsuitable because of poor ventilation and inability to properly control temperature at a sufficiently low range to produce dehydration without excessive vitamin loss. Also, precise control of humidity is impossible and air movement highly restricted.
Several special construction dehydrators have been proposed in the past. Each of those known to the Applicant has been inadequate in terms of the rate at which drying can be facilitated by dehydration of a given food while properly preserving color, flavor and quality; temperature control has been inadequate frequently resulting in incomplete drying and protracted time exposure or too high a temperature followed by excessive vitamin loss. Excessive air flow results in case hardening where the inner moisture is sealed and spoilage or inferior product results; and/or precise control of humidity conditions in the vicinity of the food being dehydrated and inadequate circulation of the air about the food has protracted dehydration or resulted in unacceptable or inferior dehydrated products.